50$ robot tutorial schematic question

[Lefteris]

Hello all,

I would like to ask a question about the 50 dollar robot tutorial, assuming I use the battery pack + 9V battery to power it.

I have finished the circuit but it does not work .. so I am trying to figure it out. Specifically the question is for this picture

Since I am doing it with DC motors and an H-bridge IC the circuit is kind of different but I wanted to ask about the  battery pack powering. As seen in that picture the AA ground is connected to the 9V ground. Is that okay?

[Ro-Bot-X]

It is absolutely necesary. If you don't connect all the grounds (negatives) together, the circuit will not work at all or not work as espected. Just DO NOT connect the positives of the different batteries together...

[Lefteris]

Okay, that's how I did it anyway. I was wondering if different grounds were needed but obviously they are not. So that is not the problem. I was especially carefull not to connect different positives together , since so many people told me NOT TO. I wonder what happens .... the battery dies? Explosion?

Most of the circuit seems to be working but I don't get the computer to identify the programmer ... (the pins are correct)

Also the voltage regulator ... I know that excess voltage ( 5V from 9V ) is turned to heat ... but how much heat exactly? When I try to touch it it is burning extremely hot. As hot as an oven stove or something. I guess that it is made to withstand heat, but I was wondering how come the plastic did not melt evne after leaving it on for 5 minutes.

[Webbot]

It should NOT be burning hot (mine are never more than room temperature). So you've probably got some form of short somewhere. Unplug the microcontroller from its seat (to stop it getting fried) until you sort out the problem.


The schematic in the file attached to this post may make connections clearer.
http://www.societyofrobots.com/robotforum/index.php?topic=3292.0

With the micro controller and servos unplugged - then turn it back on and check that you are getting the correct voltages and the voltage controller isn't getting hot. If you still have problems then you will need to use a meter to check the resistances. ie check that there isn't a short circuit between the +5v from the regulator and ground (which I think may be your problem).

Once you can leave it all turned on for a while without anything getting hot - then plug the microcontroller and servos back in.